vCenter database problem during upgrade to 6.0 Update 1

I was upgrading a vCenter from 5.5 Update 2e  to 6.0 Update 1.

The first thing i did was to convert there vCenter 5.5  from Windows version to vCSA 5.5, and that went good after some certificate replacement.

Then I tried to upgrade the vCSA 5.5 to vCSA 5.0 Update but, during the checks that done on the old vCSA 5.5 i came back with this message:

Source vCenter Server schema validation found an issue. vcsa

So i started looking thru logfiles on the vCSA 5.5, in this log: /var/log/vmware/upgrade/vcdb_req.err i found this at the bottom:

1 [P0001](7) ERROR: ERROR ! Extra sequences: vpx_inventory_seq;; Error while executing the query

this message says the there is configured/defined a sequence called vpx_inventory_seq. This i related to a database table called vpx_inventory with does not exist any more, this is from an old version of vCenter, and the table was deleted during former upgrades, but not the sequence, so the solution was to drop this:

DROP SEQUENCE vpx.vpx_inventory_seq;

I did this thru the pgadmin3, where i connected to the vCSA's vPostgres database. To enable access i used this information: http://nilic.github.io/2015/03/21/exploring-vcsa-embedded-postgresql-database/

You can also do this from the prompt of the vCSA, or thru SSH:

/opt/vmware/vpostgres/current/bin/psql -U postgres -d VCDB -c "DROP SEQUENCE vpx.vpx_inventory_seq"